In the past, the absorption field or subsurface tile structure of septic tank and sanitation systems has consisted of a field of 12 inch lengths of four inch architectural drain tile, 2 to 3 foot lengths of vertured clay sewer pipe, or extended lengths of perforated, non-metallic pipe. These fields are laid in such a manner that the effluent flow from the septic tank is distributed with reasonable uniformity to the ambit soil.
It is considered essential to have a distribution box or similar means in each absorption field to divert the effluent into separate pipe systems. In other words, the purpose of the box or junction is to insure equal distribution of the effluent from the septic tank into the various lateral lines. The main purpose of the junction is to prevent overloading and thus failure of one of the lines while the other line or lines are left empty.
Plain pipe fittings in the form of T's and Y's have been proposed to replace distribution boxes but they have been found not to give even distribution. Even using distribution boxes, the same must be installed in a perfectly level condition or more effluent will move into one line than the other thus causing the problems outlined above.
One earlier solution to the above-indicated problems was the present invention Distribution Means disclosed in U.S. Pat. No. 3,497,067, where a distribution box or modified T included a flow divider with a knife edge which, even though the box or joint was not level, would allow the flow of effluent to still be almost evenly divided into each of the different distribution lines.
Although the above system has proved successful in commercial use, there can still be a buildup of solid particles on or around the knife edge of the divider, particularly when the effluent is moving slowly, and can, if not eliminated, eventually cause uneven flow and defeat the purpose of the system.